TW202438943A - Method for manufacturing optical laminate and optical laminate - Google Patents

Abstract

An object of the present invention is to provide an optical laminate which has great processability and conveyance performance. An optical laminate (10) comprises two optical films (11, 12) and an adhering layer (13) sandwiched between the two optical films (11, 12), wherein at least one of the two optical films (11, 12) is a polarizing plate; protruding portions protruding in a surface direction are disposed on side surfaces of the two optical films (11, 12); a side surface of the adhering layer (13) at a location corresponding to the location of the tip end of the protruding portion is positioned on the inner side than the tip end of the protruding portion; the tanδ at 70℃ of an adhesive which constitutes the adhering layer (13) is 0.30 to 0.80; a storage elastic modulus of the adhesive at 25℃ is 0.05 to 0.40 MPa; and the thickness of the adhering layer (13) is larger than or equal to 50μm. A manufacturing method of the optical laminate (10) cuts a long shape optical laminate with a blade having a shape corresponding to the protruding portion in a state of pressuring the vicinity of a cutting edge.

Description

Method for manufacturing optical laminate and optical laminate

The present invention relates to a method for manufacturing an optical laminate and the optical laminate.

Patent document 1 shows a technique for cutting using a cutting blade having a repeated concave-convex structure so that the side surface of an optical laminate including an adhesive layer becomes a repeated concave-convex structure. This technique can prevent the adhesive exposed on the side surface from overflowing.

[Prior Art Literature]

[Patent Literature]

Patent document 1: Japanese Patent Publication No. 3523118

However, simply making the side surface of the optical laminate uneven may not be able to properly prevent the adhesive from overflowing from the optical laminate. For example, if a thicker adhesive such as OCA (Optical Clear Adhesive) is used as the adhesive constituting the adhesive layer included in the optical laminate, it is difficult to properly prevent the adhesive from overflowing. The OCA contained in the adhesive layer of the optical laminate is generally soft and thick. If the side surface of the optical laminate is only made concave and convex, when multiple products (chips) are cut out from the long strip of optical laminate, the following problems may arise: the products cannot be separated individually due to being attached to adjacent products, they may be attached to the conveyor rails during transportation, or adhesive stains may be generated due to friction. Such optical laminates may cause problems in processability and transportability.

This invention was developed based on the above-mentioned topic, and its purpose is to provide a manufacturing method and optical laminate with excellent processability and transportability.

To achieve the above-mentioned object, the manufacturing method of the optical laminate of the present invention is: the manufacturing method of the optical laminate, wherein the optical laminate comprises two optical films and an adhesive layer sandwiched by the two optical films, and in the optical laminate: at least one of the two optical films is a polarizing plate; the side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other; the side surface of the adhesive layer at a position corresponding to the position of the front end of the convex portion is located closer to the front end of the convex portion than the position of the front end of the convex portion. The adhesive constituting the adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40 MPa at 25°C; the thickness of the adhesive layer is 50 μm or more; and the elongated optical laminate including two optical films and the adhesive layer sandwiched by the two optical films is pressurized near the cutting edge, and the elongated optical laminate is cut along the lamination direction of the elongated optical laminate using a blade having a shape corresponding to the convex portion.

In the optical laminate manufactured by the manufacturing method of the optical laminate of the present invention, the side surface of the adhesive layer is located further inward than the front end of the convex portion of the optical film, so that the adhesive can be properly prevented from overflowing from the optical laminate. Therefore, according to the manufacturing method of the optical laminate of the present invention, an optical laminate with excellent processability and transportability can be provided.

In order to properly and accurately manufacture the above-mentioned optical laminate, the manufacturing method of the optical laminate can also be set as the following steps.

The cutting can also be performed while applying tension to the long strip of optical laminate in a direction substantially perpendicular to the cutting edge and along the surface direction of the long strip of optical laminate.

The blade tip can also be set at an angle of 40°.

Alternatively, the long strip of optical laminate may be cut along a first direction using two approximately parallel blades, and after cutting in the first direction, the long strip of optical laminate may be cut along a second direction in a manner that forms a cutting surface that intersects with the cutting surface in the first direction.

In addition, the optical laminate of the present invention comprises two optical films and an adhesive layer sandwiched by the two optical films, and in the optical laminate: at least one of the two optical films is a polarizing plate; the side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other; the side surface of the adhesive layer at a position corresponding to the position of the front end of the convex portion is located more inward than the position of the front end of the convex portion; the adhesive constituting the adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40MPa at 25°C; and the thickness of the adhesive layer is 50μm or more.

In order to improve the processability and handling performance of the optical laminate, the optical laminate can also be constructed as follows.

The concave portion may also be provided in a manner adjacent to the convex portion of the side surfaces of the two optical films.

The convex part and the concave part may also be arranged continuously.

The angle of the protrusion formed by the lines connecting the front end of the protrusion and the two ends of the protrusion can also be 170° to 120°, and the protrusion length of the protrusion belonging to the protrusion length of the protrusion can be 0.1 to 0.5 mm.

The maximum difference between the front end of the protrusion and the side surface of the adhesive layer along the protruding direction of the protrusion can also be 20 to 100 μm.

According to the present invention, an optical laminate with excellent processability and transportability can be provided.

10: Optical laminates

11,12: Optical film

11a: convex part

13: Adhesive layer

20: Strip-shaped optical laminate

21,22: Optical film

23: Adhesive layer

100: Cutting blade

110: Plate-shaped components

120: Pressurized components

L1, L2: length

P: Pitch

θ1,θ2: angle

FIG1 is a diagram showing the end of an optical multilayer body according to an embodiment of the present invention when viewed from the side.

FIG2 is a diagram showing the end of the optical laminate of the embodiment of the present invention when viewed from the lamination direction.

FIG3 schematically shows the cutting (manufacturing) of an optical laminate from a long strip of optical laminate.

FIG4 is a diagram showing a portion of the blade tip of a cutting blade used to cut a long strip of optical laminate.

Figure 5 is a diagram schematically showing a cutting blade when cutting a long strip of optical laminate.

FIG6 is a diagram showing various examples of pressurizing components used for cutting long strips of optical laminates.

The following is a detailed description of the manufacturing method of the optical laminate and the implementation of the optical laminate of the present invention together with the drawings. In addition, the same elements in the description of the drawings are marked with the same symbols, and repeated descriptions are omitted. Furthermore, the size ratio of the drawings is not necessarily consistent with the size ratio of the object to be described.

FIG. 1 and FIG. 2 show an optical laminate 10 of the present embodiment. The optical laminate 10 is a laminate having a plurality of optical films laminated thereon. The optical laminate 10 includes an adhesive layer sandwiched between two optical films among the plurality of optical films. At least one of the two optical films is a polarizing plate. The optical laminate 10 shown in FIG. 1 and FIG. 2 includes: two optical films 11, 12, and an adhesive layer 13 sandwiched between the two optical films 11, 12. The optical laminate 10 is formed, for example, in a roughly rectangular shape when viewed from the lamination direction of the optical films. That is, the optical laminate 10 has a roughly rectangular main surface. However, the shape of the main surface of the optical laminate 10 does not necessarily have to be rectangular.

FIG. 1 is a diagram showing the end of the side surface of the optical laminate 10, that is, a diagram showing the end of the optical laminate 10 viewed from a direction perpendicular to the stacking direction. FIG. 2 is a diagram showing the end of the main surface of an optical film 11 as one of the main surfaces of the optical laminate 10, that is, a diagram showing the end of the optical laminate 10 viewed from the stacking direction of the optical film. In FIG. 2, a portion of the adhesive layer 13 (hidden by the optical film 11) is shown as a shaded portion.

The optical laminate 10 is, for example, a part used in a display. In this case, the optical film 11 is a polarizing plate, and the optical film 12 is a protective film or a separator film. The adhesive constituting the adhesive layer 13 is OCA. The optical laminate 10 (a part thereof) is combined with a cover glass and an OLED (organic light emitting diode) to form a display. When forming a display, the adhesive layer 13 formed by OCA is used to bond the polarizing plate (optical film 11) to the cover glass.

In addition, the adhesive constituting the adhesive layer 13 may be an adhesive other than OCA.

The polarizing plate at least includes a polarizing film, and generally includes a thermoplastic resin film, which is bonded to one or both sides of the polarizing film. In addition, the polarizing plate may include a protective film or a separator film on the surface opposite to the surface on which the adhesive layer 13 is laminated.

Thermoplastic resin film can be a protective film for protecting polarizers, etc. The protective film can be a phase difference film, and the following resin films such as an anti-reflection treatment layer can be provided.

Thermoplastic resin films are films independently composed of light-transmitting thermoplastic resins. The thermoplastic resin constituting the thermoplastic resin film may be an optically transparent thermoplastic resin. The thermoplastic resin used to constitute the thermoplastic resin film may be, for example: polyolefin resins such as chain polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); cellulose resins such as cellulose triacetate and diacetyl cellulose; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; and methyl methacrylate resins. (Meth) acrylic resins; polystyrene resins; polyvinyl chloride resins; acrylonitrile/butadiene/styrene resins; acrylonitrile/styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; modified polyphenylene ether resins; polysulfone resins; polyethersulfone resins; polyarylate resins; polyamide imide resins; polyimide resins, etc.

Thermoplastic resin film is a resin film that can be layered on its surface. Examples of such resin layers include: hard coating layer, anti-glare layer, anti-reflection layer, anti-static layer, anti-fouling layer, etc. Thermoplastic resin film can be attached to the polarizer via a bonding agent layer or an adhesive layer.

The thickness of the polarizing plate is usually between 25μm and 500μm.

The protective film and the separator film are films used to protect the surface of the polarizing plate and are attached to the surface of the polarizing plate in a removable manner. The protective film and the separator film can be composed of a base film and an adhesive layer laminated thereon. When the protective film is peeled off from the polarizing plate, the base film and the adhesive layer are peeled off from the polarizing plate together. When the separator film is peeled off from the polarizing plate, only the base film is peeled off, and the adhesive layer remains on the surface of the polarizing plate.

The substrate film can be composed of, for example, polyolefin resins such as polyethylene resins, polypropylene resins, cyclic polyolefin resins, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polycarbonate resins, (meth)acrylic resins, etc. The substrate film can be a single-layer structure or a multi-layer structure. The adhesive layer can be composed of (meth)acrylic adhesives, epoxy adhesives, polyurethane adhesives, silicone adhesives, etc. In addition, the protective film can be a self-adhesive resin film such as polypropylene resins and polyethylene resins. In this case, the protective film does not have an adhesive layer.

The sides of the two optical films 11 and 12 sandwiching the adhesive layer 13 are provided with convex portions (mountain portions) protruding along the surface direction of the optical films at positions facing each other. Concave portions (valley portions) can be provided in a manner adjacent to the convex portions of the sides of the two optical films 11 and 12. The convex portions and the concave portions can be provided continuously.

When viewed from the stacking direction shown in FIG. 2 , the side surface of the optical film 11 is provided with a convex portion 11a protruding along the surface direction of the optical film. The front end of the convex portion 11a is formed into a curved shape. The convex portions 11a are provided continuously and periodically, and the portions between the convex portions 11a form concave portions. The concave portions are also formed into a curved shape. In this way, the side surface of the optical film 11 is formed into a wave-like shape. Furthermore, the end of the optical film 12 facing the optical film 11 is also formed into the same shape as the end of the optical film 11.

The protrusion angle (angle θ1 shown in FIG. 2) formed by the lines connecting the front end of the protrusion 11a and the two ends of the protrusion 11a can be 170° to 120°, and the protrusion length of the protrusion belonging to the protrusion of the protrusion 11a can be 0.1 to 0.5 mm (length L1 shown in FIG. 2).

The adhesive constituting the adhesive layer 13 has a tanδ (viscoelasticity loss coefficient) of 0.30 to 0.80 at 70°C, and a storage elastic modulus of the adhesive at 25°C of 0.05 to 0.40 MPa. The tanδ of the adhesive at 70°C may be 0.30 to 0.60, or 0.30 to 0.50. The storage elastic modulus of the adhesive at 25°C may be 0.05 to 0.30 MPa, or 0.05 to 0.20 MPa. The thickness of the adhesive layer 13 is 50 μm or more. The thickness of the adhesive layer 13 may be 75 μm or more, or 100 μm or more.

The tanδ of the adhesive at 70℃ is measured by making a cylindrical test piece with a diameter of 8mm and a thickness of 600μm, which is composed of the adhesive to be measured. The dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC Co., Ltd.) is used to measure the torsional shearing method at a frequency of 1Hz with an initial strain of 1N at a temperature of 70℃.

Normally, when the thickness of the adhesive layer 13 is greater than 50 μm, when a plurality of products (small pieces) are cut out from a long optical laminate, the products may be attached to adjacent products and cannot be separated individually, or may be attached to the conveyor rail during transportation, or may be stained with adhesive due to friction, etc., resulting in poor processability and transportability. However, according to the present embodiment, an optical laminate with excellent processability and transportability can be provided even if the thickness of the adhesive layer 13 is greater than 50 μm. In particular, when the thickness of the adhesive layer 13 is greater than 100 μm, the above-mentioned adverse condition will occur more significantly. However, according to this embodiment, even if the thickness of the adhesive layer 13 is greater than 100 μm, an optical laminate with excellent processability and transportability can still be provided.

As shown in Fig. 1 and Fig. 2, the side surface of the adhesive layer 13 at the position corresponding to the front end position of the convex portion of the optical film 11, 12 is located further inward than the front end position of the convex portion. That is, in the portion corresponding to the convex portion of the optical film 11, 12, the adhesive layer 13 is more concave than the optical film 11, 12. The side surface of the optical laminate 10 shown in Fig. 1 is the side surface (cross section) of the front end of the convex portion of the optical film 11, 12. As shown in Fig. 1(a), the side surface of the adhesive layer 13 in this portion can be curvedly concave from the protruding direction of the convex portion as it moves away from the optical film 11, 12 along the lamination direction of the optical film 11, 12. Alternatively, as shown in FIG. 1(b), the side surface of the adhesive layer 13 in this portion may be formed in a straight line along the lamination direction of the optical films 11 and 12 at a position recessed from the front end of the optical films 11 and 12.

The maximum difference between the front end of the protrusion of the optical film 11, 12 and the side surface of the adhesive layer 13 along the direction in which the protrusion protrudes can be 20 to 100μm. When cutting multiple products (small pieces) from a long strip of optical laminate, the maximum difference is preferably 60 to 100μm from the perspective of making it easy to separate the products individually while the products are connected to adjacent products.

The side surface of the adhesive layer 13 in this part covers the entire lamination direction of the optical films 11 and 12 and is located further inward than the front end of the protrusion of the optical films 11 and 12. For example, as shown in FIG1(c), even if the side surface of the adhesive layer 13 has a portion located further inward than the front end of the protrusion of the optical films 11 and 12, the side surface of the adhesive layer 13 still has a portion flush with the front end of the protrusion of the optical films 11 and 12 or a portion protruding further than the front end, it does not belong to the optical laminate 10 of this embodiment.

The above-mentioned structure of the side surface of the optical multilayer body 10 covers the entire side surface. However, the above-mentioned structure of the side surface of the optical multilayer body 10 may also be the structure of only a part of the side surface.

The above-mentioned structure of the side surface of the optical laminate 10 is used to appropriately prevent the adhesive from overflowing from the adhesive layer 13. The optical laminate 10 of this embodiment is manufactured by cutting out from a long strip of optical laminate as described later. The optical laminate 10 can be a single-piece small piece cut from a long strip of optical laminate belonging to a large-sized sheet.

As described above, when the adhesive overflows from the optical laminate, during the above-mentioned cutting, it may cause the optical laminate to be attached to the adjacent optical laminate and unable to be separated individually, or it may be attached to the conveyor belt guide during transportation, or adhesive stains may be generated due to friction. According to the above-mentioned structure of the side surface of the optical laminate 10, the above-mentioned problems of processing and transportability can be prevented. From the above-mentioned viewpoint, the above-mentioned value of the optical laminate 10 is to obtain a suitable optical laminate 10.

The above problem will occur even if the adhesive layer used for the polarizing plate is 50μm or more. In other words, if the optical laminate contains at least one adhesive layer with a thickness of 50μm or more, the above problem will occur.

The side surface of the optical laminate 10 of this embodiment has unevenness, so the side surface of the optical laminate 10 must be set to be flat according to the product manufactured using the optical laminate 10. In this case, the side surface of the optical laminate 10 can be polished. In this case, the size of the optical laminate 10 can include a grinding margin (for example, 1 mm).

The above-mentioned structure of the side surface of the optical laminate 10 is realized by the manufacturing method of this embodiment. Next, the manufacturing method of the optical laminate 10 of this embodiment is described. In this manufacturing method, a long strip of optical laminate from which the optical laminate 10 can be cut is prepared in advance. The long strip of optical laminate has the same laminate structure as the optical laminate 10. That is, in this embodiment, the components of the long strip of optical laminate include: two optical films, and an adhesive layer sandwiched by the two optical films. The materials of the two optical films and adhesive layer constituting the long strip optical laminate are the same as those of the two optical films 11, 12 and adhesive layer 13 constituting the optical laminate 10. When the long strip optical laminate is viewed from the lamination direction (the surface perpendicular to the lamination direction), it has a size that can be cut out of the optical laminate 10.

In the manufacturing method of this embodiment, the optical laminate 10 is manufactured by cutting out the optical laminate 10 from the long strip optical laminate. For example, the four sides of the optical laminate 10 with a substantially rectangular main surface are cut out from the long strip optical laminate. Moreover, a plurality of optical laminates 10 can be cut out from the long strip optical laminate. The cut plurality of optical laminates 10 can be adjacent to each other.

Cutting out the optical laminate 10 from the long strip optical laminate is performed by cutting the sides of the optical laminate 10 from the long strip optical laminate using a cutting blade. For example, as shown in FIG3, while the long strip optical laminate 20 (raw material) is being transported, a plate-shaped member 110 equipped with a cutting blade 100 is pressed against the long strip optical laminate 20, thereby cutting out the optical laminate 10. In the example shown in FIG3, two adjacent optical laminates 10 are cut out.

It is not necessary to cut all sides of the optical laminate 10 of the long optical laminate 20 at the same time. In the example shown in FIG. 3, the two sides parallel to the transport direction are cut first, and then the two sides perpendicular to the transport direction are cut. As shown in FIG. 3, the cutting blade 100 can be installed on the plate-like component 110 at the position corresponding to the cut side. As shown in FIG. 3, the cutting blade 100 for cutting the two sides parallel to the transport direction and the cutting blade 100 for cutting the two sides perpendicular to the transport direction are installed on the plate-like component 110 in advance, so that the cutting of the individual optical laminate 10 can be performed at the same time.

Thus, in the manufacturing method of this embodiment, the long strip optical laminate 20 is cut along a first direction (e.g., a direction parallel to the transport direction) by two substantially parallel cutting blades 100, and after cutting in the first direction, the long strip optical laminate 20 is cut along a second direction (e.g., a direction perpendicular to the transport direction) in a manner that a cutting surface intersecting with the cutting surface in the first direction is formed.

The cutting blade 100 used for cutting the edge of the optical laminate 10 is a blade having a shape corresponding to the convex parts of the two optical films 11, 12 of the optical laminate 10. For example, the cutting blade 100 is a wavy blade. FIG. 4 shows a portion of the blade tip of the cutting blade 100 as a wavy blade as viewed from the direction pressed against the long strip optical laminate 20. As shown in FIG. 4, the blade tip of the cutting blade 100 is formed into a repeated concave-convex structure corresponding to the convex parts and concave parts of the two optical films 11, 12 of the optical laminate 10. For example, as shown in FIG. 4, the repeated pitch P in the cutting blade 100 is 2 mm, and the protruding length L2 of the convex part relative to the concave part is 0.3 mm.

FIG. 5 schematically shows a cutting blade 100 when cutting a long strip optical laminate 20. The long strip optical laminate 20 is a laminate of optical films 11, 12 and adhesive layer 13, optical films 21, 22 and adhesive layer 23 that will form the optical laminate 10. FIG. 5 is a view viewed from the long side direction of the cutting blade 100, and the cutting side is the longitudinal direction of the drawing. The blade tip angle θ2 of the cutting blade 100 shown in FIG. 5 can be greater than 40°. In addition, the angle can be any one of greater than 45°, greater than 50° and greater than 60°. As shown by the arrow in FIG5 , when the long strip optical laminate 20 is cut by the cutting blade 100 , the taper (angle of the blade tip) of the cutting blade 100 will apply stress in the lateral direction (surface direction) to the long strip optical laminate 20 .

In the manufacturing method of this embodiment, the cutting of the long optical laminate 20 by the cutting blade 100 is performed under the condition of applying pressure near the cutting edge of the long optical laminate 20. The pressurization near the cutting edge of the long optical laminate 20 is performed, for example, as shown in FIG5 , by pressing two pressurizing members 120 against the long optical laminate 20 at both ends of the cutting blade 100. The pressurizing member 120 is, for example, an elastic body such as a sponge. The pressurizing member 120 is a member that is longer (length in the longitudinal direction in FIG5 ) than the cutting blade 100. The cutting of the long strip optical laminate 20 can also be performed without applying pressure to the vicinity of the cutting edge of the long strip optical laminate 20. For example, the cutting of the long strip optical laminate 20 can be performed only in a state where pressure is applied to the vicinity of the cutting edge of the long strip optical laminate 20.

The hardness of the elastic body used for pressurization is measured by a rubber hardness tester based on the physical test method of SRIS-0101 of the Japan Rubber Association standard specification, and can be 20 to 60, or even 20 to 35.

The pressurizing member 120 can be pre-installed on the plate-shaped member 110 in the same manner as the cutting blade 100. For example, for each cutting blade 100, two pressurizing members 120 are installed on the plate-shaped member 110 to sandwich the cutting blade 100. When the cutting blade 100 is pressed against the long optical laminate 20, the pressurizing member 120 is set to press the two ends of the cutting edge. In addition, the pressurization near the cutting edge can also be performed by a method other than pressing with the pressurizing member 120.

The pressurized area can be set to less than 15 mm on both sides of the cutting edge. Furthermore, the pressurized area can be set to less than 10 mm on both sides of the cutting edge. In addition, the pressurized area (its lower limit) can be set to more than 3 mm on both sides of the cutting edge. Furthermore, the pressurized area (its lower limit) can be set to more than 5 mm on both sides of the cutting edge. In addition, the above distance may not be the distance from the cutting edge, but may be the distance from the long side of the cutting blade 100 (the long side of the blade tip of the cutting blade 100 shown in FIG. 4) that contacts the long strip optical laminate 20. The above pressurized area may be an area near the cutting edge, and the surrounding area may also be an area that is not pressurized.

In this way, the sides of the optical laminate 10 are cut from the long strip optical laminate 20, so that the cut optical laminate 10 (its side surfaces) becomes the above-mentioned structure.

In the manufacturing method of this embodiment, the long strip optical laminate 10 can be cut while applying tension in a direction substantially perpendicular to the cutting edge and along the surface direction of the long strip optical laminate 20. The tension is applied so that the cutting blade 100 can properly cut the adhesive layer 23 and prevent the cut optical laminate 10 from being attached to the long strip optical laminate 20 or another optical laminate 10. The direction in which the tension is applied is the direction in which the cut long strip optical laminate 20 is separated from each other. For example, in FIG5 , the tension is applied in the left-right direction. The application of tension is performed, for example, by holding the two ends of the long strip optical laminate 20 in the direction of applying tension, and pulling one or both sides of the held portion. In addition, the application of tension can be performed by any known method other than the above.

In order to properly cut the adhesive layer 23 and prevent the cut optical laminate 10 from reattaching, the force applied to the long strip optical laminate 20 can be applied by a pressurizing member 120 (such as the elastic body mentioned above) for pressurizing the cutting edge of the long strip optical laminate 20. For example, in order to achieve the above, the shape of the pressurizing member 120 is set to be farther away from the cutting blade 100 than the root of the cutting blade 100 as shown in Figures 6(a) to 6(d). In addition, Figure 6 is a diagram viewed from the long side direction of the cutting blade 100, just like Figure 5.

For example, as shown in FIG6(a), the surface of the pressurizing member 120 on the cutting blade 100 side can be tilted in a manner that moves away from the cutting blade 100 as it moves toward the front end of the cutting blade 100. In addition, as shown in FIG6(b), the corner of the front end of the cutting blade 100 side of the pressurizing member 120 can be set to a C chamfer. In addition, as shown in FIG6(c), the corner of the front end of the cutting blade 100 side of the pressurizing member 120 can be set to an R chamfer. In addition, in addition to the shape of the cutting blade 100 side of the pressurizing member 120, the surface on the opposite side to the cutting blade 100 can also be tilted in a manner that moves away from the cutting blade 100 as it moves toward the front end of the cutting blade 100, as shown in FIG6(d).

The pressurizing member 120 is set to the above-mentioned shape, so that as shown in FIG6(e), when the long strip optical laminate 20 is cut by the cutting blade 100, when the pressurizing member 120 is pressed against the long strip optical laminate 20, the pressurizing member 120 will be deformed to be away from the cutting blade 100. By this deformation, the pressurizing member 120 applies a force from the cutting edge to the outside to the long strip optical laminate 20. In this way, the adhesive layer 23 can be properly cut and the cut optical laminate 10 can be prevented from reattaching.

In order to perform proper cutting, the angle of the side surface of the cutting blade 100 of the pressurizing member 120 shown in FIG. 6(d) and the like, which moves away from the cutting blade 100 as it moves toward the front end of the cutting blade 100 (the angle between a straight line directly below the blade tip and the above surface of the pressurizing member 120) can be set to 0° to 30°. Alternatively, in order to perform proper cutting, the angle can be set to 5° to 20°. When a sponge is used as the pressurizing member 120, if the angle exceeds 30°, the force of the pressurizing member 120 on the long strip of optical laminate 20 will be weakened.

The numerical values of the manufacturing method of the optical laminate 10 mentioned above are used to appropriately manufacture the optical laminate 10. The above is the manufacturing method of the optical laminate 10 of this embodiment.

In the optical laminate 10 of this embodiment, the side surface of the adhesive layer 13 is located further inward than the front end of the convex portion of the optical film 11, 12, so that the adhesive can be properly prevented from overflowing from the optical laminate 10. Therefore, the optical laminate 10 of this embodiment has excellent processability and transportability. For example, when the optical laminate 10 is manufactured, the optical laminate 10 can be easily separated separately. In addition, it can prevent the optical laminate 10 from being attached to the conveyor belt guide rail during transportation and stains. In addition, the sticky feeling when handling the optical laminate 10 can also be eliminated.

In order to make the processability and transportability of the optical multilayer body 10 better, the optical multilayer body 10 of the above-mentioned embodiment can be set to the following structure.

The concave portion can be provided in a manner adjacent to the convex portion of the side surface of the two optical films 11 and 12. In addition, in the optical films 11 and 12, the convex portion and the concave portion can be provided continuously. That is, the side surface of the optical films 11 and 12 can also be formed into a wave shape in which the convex portion and the concave portion are continuous. However, the two optical films 11 and 12 of the optical laminate 10 can be configured to have at least one convex portion provided.

The convex angle between the front end of the convex portion and the lines connecting the two ends of the convex portion in the optical films 11 and 12 is 170° to 120°, and the convex protrusion length belonging to the length of the protrusion is 0.1 to 0.5 mm. However, the convex angle and the convex protrusion length may not fall within the above range.

The maximum difference between the front end of the protrusion along the direction in which the protrusion of the optical film 11, 12 protrudes and the side surface of the adhesive layer can be 20 to 100μm. However, the maximum difference may not fall within the above range.

In addition, according to the manufacturing method of the optical multilayer body 10 of this embodiment, the optical multilayer body 10 of this embodiment can be manufactured.

In order to properly and accurately manufacture the optical laminate 10, the manufacturing method of the optical laminate 10 in the above-mentioned embodiment can also be set as the following steps.

Cutting can be performed while applying tension to the long strip optical laminate 20 in a direction substantially perpendicular to the cutting edge and along the surface direction of the long strip optical laminate 20. According to this step, the cutting edge can be easily cut when the long strip optical laminate 20 is cut, and the optical laminate 10 and the long strip optical laminate 20 can be separated more appropriately. However, it is not necessary to apply tension during cutting.

The angle of the cutting blade 100 can be set to be above 40°. According to this step, the long strip of optical laminate 20 can be properly and accurately cut. However, the angle of the cutting blade 100 may not fall within the above range.

It is also possible to cut the long strip optical laminate 20 along the first direction with two roughly parallel cutting blades 100, and after cutting in the first direction, cut the long strip optical laminate 20 along the second direction in a manner that can form a cutting surface that intersects with the cutting surface in the first direction. According to this step, the optical laminate 10 can be properly and reliably cut out from the long strip optical laminate 20. However, the cutting with the cutting blade 100 does not necessarily need to be performed in the above manner.

Next, the embodiments and comparative examples of the present embodiment are described. In the embodiments and comparative examples, a long optical laminate is cut into a plurality of roughly rectangular single-sheet optical laminates using a cutting blade. Then, a pen with a buffer rubber and double-sided tape attached to the tip is adhered to the main surface of the cut single-sheet optical laminate, and is lifted vertically and moved to another location. At this time, it is confirmed whether the moved single-sheet optical laminate can be moved in a state of being separated one by one without being connected to the adjacent single-sheet optical laminate.

In a single-sheet optical laminate, the maximum difference between the tip of the convex portion and the side surface of the adhesive layer along the direction in which the convex portion of the optical film protrudes is measured, that is, the amount of depression of the adhesive layer is measured. The measurement is performed using a microscope (VHX-5000, manufactured by Keyence).

The storage elastic modulus of the adhesive layer was measured using a cylindrical sheet with a diameter of 8 mm and a thickness of 1 mm as the test piece, and a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC Co., Ltd.) and torsional shear at a frequency of 1 Hz at temperatures of 23°C and 80°C.

First, a long strip of optical laminate was prepared in the following manner. 3 parts of carboxyl-modified polyvinyl alcohol [KL318 manufactured by Kuraray Co., Ltd.] was dissolved in 100 parts of water, and 1.5 parts of polyamide epoxy additive [Sumirez Resin 650 (30) manufactured by Sumika Chemtex Co., Ltd., an aqueous solution with a solid content of 30%] as a water-soluble epoxy resin was added to the aqueous solution to prepare a water-based adhesive (water-soluble adhesive).

A 30μm thick polyvinyl alcohol film (average degree of polymerization of about 2,400, saponification degree of 99.9 mol% or more) was stretched to about 5 times in one axis by dry stretching, and then immersed in 60°C pure water for 1 minute while maintaining the stretched state, and then immersed in an aqueous solution of iodine/potassium iodide/water with a weight ratio of 0.05/5/100 at 28°C for 60 seconds. Then, it was immersed in an aqueous solution of potassium iodide/boric acid/water with a weight ratio of 8.5/8.5/100 at 72°C for 300 seconds. Then, it was washed with 26°C pure water for 20 seconds and dried at 65°C to obtain a 12μm thick polarizer with iodine adsorbed and aligned on the polyvinyl alcohol film.

A transparent protective film made of cellulose triacetate [KC2UA manufactured by Konica Minolt Co., Ltd., thickness 25μm] was laminated on one surface of the prepared polarizer using the above-mentioned aqueous adhesive, and a transparent protective film made of cycloolefin polymer [product name "ZF14" manufactured by ZEON Co., Ltd., Japan, thickness 23μm] was laminated on the other surface of the prepared polarizer using the above-mentioned aqueous adhesive, and then dried at 80°C for 5 minutes to obtain a polarizing plate. In addition, before lamination, the transparent protective film made of cellulose triacetate was saponified, and the bonding surface of the transparent protective film made of cycloolefin polymer and the polarizer was subjected to corona treatment.

Next, prepare a commercially available adhesive. The commercially available adhesive is a 220μm adhesive layer formed on the release-treated surface of a 100μm thick protective film that has been subjected to release treatment. The above-mentioned adhesive layer is an adhesive layer sandwiched between two optical films in the long strip optical laminate to be produced. The above-mentioned protective film is an optical film that sandwiches the adhesive layer together with the above-mentioned polarizing plate in the long strip optical laminate to be produced.

An adhesive layer with a protective film is laminated on the surface of a transparent protective film made of triacetyl cellulose of the prepared polarizing plate to produce a long strip optical laminate. The prepared long strip optical laminate is formed as a laminate of polarizing plate/adhesive layer/protective film (corresponding to optical film 11/adhesive layer 113/optical film 12 in FIG. 1 , respectively).

In addition, the storage elastic modulus of the commercially available adhesive at 25°C is 0.06MPa, and the tanδ (loss tangent) at 70°C is 0.36. A strip of optical multilayers with a width of 600mm and a length of 100m was prepared in the above manner.

In the embodiments and comparative examples, the following blade types are prepared as cutting blades for cutting a single-piece optical laminate from a long strip of optical laminate.

Blade type A: A blade type in which four blades with a repetitive structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are arranged in parallel at intervals of 153 mm. As a structure for pressurizing the long optical laminate, sponges with a rectangular cross-section and a sponge hardness of 35 (the hardness measured by a rubber hardness tester based on the physical test method of SRIS-0101 of the Japanese Rubber Association standard, the same applies below) and a sponge width of 7 mm are arranged at both ends of the blade. In addition, the sponge is set to protrude 1.4 mm from the front end of the blade.

Blade type B: A blade type in which eight blades with a wave-shaped repetitive structure (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are arranged in parallel at intervals of 168 mm. As a structure for pressurizing the long optical laminate, sponges with a rectangular cross-section, a sponge hardness of 35, and a sponge width of 7 mm are arranged at both ends of the blade. In addition, the sponge is set to protrude 1.4 mm from the front end of the blade.

Blade type C: A blade type in which four blades with a repetitive structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are prepared and arranged in parallel at intervals of 153 mm. As a structure for pressurizing the long optical laminate, a sponge with a hardness of 35 and a width of 7 mm is arranged at both ends of the blade, with the cross section tilted outward toward the blade tip as shown in Figure 6 (d). In addition, the sponge is set to protrude 1.4 mm from the front end of the blade. The angle between the straight line directly below the blade tip and the straight line of the cross section of the sponge tilted outward toward the blade tip is 10°.

Blade type D: A blade type in which eight blades with a repetitive structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are arranged in parallel at intervals of 168 mm. A sponge with a hardness of 35 and a width of 7 mm is arranged at both ends of the blade, and the cross-section is tilted outward toward the blade tip as shown in Figure 6 (d) to pressurize the long optical laminate. In addition, the sponge is set to protrude 1.4 mm from the front end of the blade. The angle between the straight line directly below the blade tip and the straight line of the cross-section of the sponge tilted outward toward the blade tip is 10°.

Blade type E: A blade type in which four blades with a repetitive structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are arranged in parallel at intervals of 153 mm. As a structure for pressurizing the long optical laminate, a sponge with a rectangular cross-section and a sponge hardness of 35 is arranged without intervals in the area without blades. In addition, the sponge is set to protrude 1.4 mm from the front end of the blade.

Blade type F: A blade type in which eight blades with a repetitive structure of wave-shaped concave and convex (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) are prepared and arranged in parallel at intervals of 168 mm. As a structure for pressurizing the long optical laminate, a sponge with a rectangular cross-section and a sponge hardness of 35 is arranged without intervals in the area without blades. In addition, the sponge is set to protrude 1.4 mm from the front end of the blade.

Blade type G: A blade type that has four blades with a wave-shaped repetitive structure (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) arranged in parallel at intervals of 168 mm.

Blade type H: A blade type that has eight blades with a wave-shaped repetitive structure (NCEW07 manufactured by Nakayama Co., Ltd., product code: 338216) arranged in parallel at intervals of 168 mm.

Blade type G and blade type H do not have a structure such as a sponge to pressurize the long strip of optical laminate.

As Example 1, while the manufactured long strip optical laminate is being transported and stopped, blade type A is used to cut the long strip optical laminate. The blade of blade type A is used so as to be arranged parallel to the transport direction of the long strip optical laminate. Next, blade type B is used to cut the long strip optical laminate. Blade type B is used so as to be arranged perpendicular to the transport direction of the long strip optical laminate. The optical laminate cut in the above manner is a roughly rectangular optical laminate of 153 mm × 168 mm, and 21 optical laminates can be obtained. After cutting, all optical laminates are not attached to adjacent optical laminates, and the separation of the optical laminates is excellent. The amount of depression of the adhesive layer in the direction where the convex part of the optical film protrudes is 20 to 50μm.

As Example 2, while the manufactured long strip optical laminate is being transported and stopped, a blade type C is used to cut the long strip optical laminate. The blade of the blade type C is used so as to be arranged parallel to the transport direction of the long strip optical laminate. Next, a blade type D is used to cut the long strip optical laminate. The blade type D is used so as to be arranged perpendicular to the transport direction of the long strip optical laminate. The optical laminate cut in the above manner is a roughly rectangular optical laminate of 153 mm×168 mm, and 21 optical laminates can be obtained. After cutting, all optical laminates are not attached to adjacent optical laminates, and the separation of the optical laminates is excellent. The amount of depression of the adhesive layer in the direction where the convex part of the optical film protrudes is 60 to 100μm.

As Comparative Example 1, while the manufactured long strip optical laminate is being transported and stopped, the long strip optical laminate is cut using blade type E. The blade of blade type E is used so as to be arranged parallel to the transport direction of the long strip optical laminate. Next, the long strip optical laminate is cut using blade type F. Blade type F is used so as to be arranged perpendicular to the transport direction of the long strip optical laminate. The optical laminate cut in the above manner is a roughly rectangular optical laminate of 153 mm × 168 mm, and 21 optical laminates are obtained. After cutting, all optical stacks will be attached and connected to adjacent optical stacks, and the separation of the optical stacks is not good. It is impossible to confirm the depression of the adhesive layer in the direction where the convex part of the optical film protrudes. As mentioned above, since multiple optical stacks are connected, it can be inferred that the adhesive layer of the convex part is flat or protruding.

As Comparative Example 2, while the manufactured long strip optical laminate is being transported and stopped, the long strip optical laminate is cut using blade type G. The blade of blade type G is used to be configured parallel to the transport direction of the long strip optical laminate. Next, the long strip optical laminate is cut using blade type H. Blade type H is used to be configured perpendicular to the transport direction of the long strip optical laminate. The optical laminate cut in this way is not separated from the blade type after cutting, so the roughly rectangular optical laminate of 153mm×168mm cannot be recovered.

The manufacturing method of the optical multilayer body and the optical multilayer body disclosed herein have the following structure.

[1] A method for manufacturing an optical laminate, wherein:

The aforementioned optical laminate comprises two optical films and an adhesive layer sandwiched by the two optical films, and in the optical laminate:

At least one of the two aforementioned optical films is a polarizing plate;

The side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other;

The side surface of the adhesive layer at a position corresponding to the position of the front end of the protrusion is located further inward than the position of the front end of the protrusion;

The adhesive constituting the aforementioned adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40 MPa at 25°C;

The thickness of the aforementioned adhesive layer is greater than 50μm;

The manufacturing method is to cut the long strip of optical laminated body along the lamination direction using a blade having a shape corresponding to the above-mentioned convex part while applying pressure near the cutting edge of the long strip of optical laminated body including two optical films and an adhesive layer sandwiched by the two optical films.

[2] A manufacturing method as described in [1], wherein the cutting is performed while applying tension to the elongated optical laminate in a direction substantially perpendicular to the cutting edge and along the surface direction of the elongated optical laminate.

[3] The manufacturing method as described in [1] or [2], wherein the angle of the blade tip is set to be greater than 40°.

[4] A manufacturing method as described in any one of [1] to [3], wherein the long strip of optical multilayer body is cut along a first direction using two substantially parallel blades, and after cutting in the first direction, the long strip of optical multilayer body is cut along a second direction in a manner that forms a cutting surface that intersects with the cutting surface in the first direction.

[5] An optical laminate comprising two optical films and an adhesive layer sandwiched between the two optical films, and in the optical laminate:

At least one of the two aforementioned optical films is a polarizing plate;

The side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other;

The side surface of the adhesive layer at a position corresponding to the position of the front end of the protrusion is located further inward than the position of the front end of the protrusion;

The adhesive constituting the aforementioned adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40 MPa at 25°C;

The thickness of the adhesive layer is greater than 50μm.

[6] An optical laminate as described in [5], wherein a concave portion is provided in a manner adjacent to the convex portion of the side surfaces of the two optical films.

[7] The optical multilayer body as described in [6], wherein the convex portion and the concave portion are arranged continuously.

[8] An optical multilayer as described in any one of [5] to [7], wherein the angle of the protrusion formed by the lines connecting the front end of the protrusion and the two ends of the protrusion is 170° to 120°, and the protrusion length of the protrusion belonging to the length of the protrusion of the protrusion is 0.1 to 0.5 mm.

[9] An optical multilayer body as described in any one of [5] to [8], wherein the maximum difference between the front end of the protrusion and the side surface of the adhesive layer along the protruding direction of the protrusion is 20 to 100 μm.

10: Optical laminates

11,12: Optical film

13: Adhesive layer

Claims (9)

A method for manufacturing an optical laminate, wherein: The aforementioned optical laminate comprises two optical films and an adhesive layer sandwiched by the two optical films, and in the optical laminate, At least one of the two aforementioned optical films is a polarizing plate; The side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other; The side surface of the adhesive layer at a position corresponding to the position of the front end of the protrusion is located further inward than the position of the front end of the protrusion; The adhesive constituting the aforementioned adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40 MPa at 25°C; The thickness of the aforementioned adhesive layer is greater than 50μm; The manufacturing method is to cut the long strip of optical laminated body along the lamination direction using a blade having a shape corresponding to the above-mentioned convex part while applying pressure near the cutting edge of the long strip of optical laminated body including two optical films and an adhesive layer sandwiched by the two optical films. The manufacturing method as described in claim 1, wherein the cutting is performed while applying tension to the elongated optical laminate in a direction substantially perpendicular to the cutting edge and along the surface direction of the elongated optical laminate. A manufacturing method as described in claim 1 or 2, wherein the angle of the blade tip is set to be greater than 40°. A manufacturing method as described in claim 1 or 2, wherein the aforementioned long strip optical laminate is cut along a first direction with two substantially parallel blades, and after cutting in the first direction, the long strip optical laminate is cut along a second direction in a manner that forms a cutting surface that intersects with the cutting surface in the first direction. An optical laminate includes two optical films and an adhesive layer sandwiched by the two optical films, and in the optical laminate, At least one of the two aforementioned optical films is a polarizing plate; The side surfaces of the two optical films are provided with convex portions protruding along the surface direction of the optical films at positions facing each other; The side surface of the adhesive layer at a position corresponding to the position of the front end of the protrusion is located further inward than the position of the front end of the protrusion; The adhesive constituting the aforementioned adhesive layer has a tanδ of 0.30 to 0.80 at 70°C, and a storage elastic modulus of 0.05 to 0.40 MPa at 25°C; The thickness of the adhesive layer is greater than 50μm. The optical multilayer body as described in claim 5, wherein a concave portion is provided in a manner adjacent to the convex portion of the side surfaces of the two optical films. An optical multilayer as described in claim 6, wherein the convex portion and the concave portion are disposed continuously. An optical multilayer as described in any one of claims 5 to 7, wherein the angle of the protrusion included by the lines connecting the front end of the protrusion and the two ends of the protrusion is 170° to 120°, and the protrusion length of the protrusion belonging to the length of the protrusion of the protrusion is 0.1 to 0.5 mm. An optical multilayer as described in any one of claims 5 to 7, wherein the maximum difference between the front end of the protrusion and the side surface of the adhesive layer along the direction in which the protrusion protrudes is 20 to 100 μm.

Images